System.Web.Mvc.Html.MvcForm Razor show me a HTML

I have a form in a View.

@if (Request.IsAuthenticated) {

     @(Html.BeginForm("LeaveComment", "Publication")){

          <input type="text" name="pub" style="display: none" value=@publication.PublicationID>

          <input type="text" name="mail"  style="display: none" value=@Context.User.Identity.Name>

          <textarea id="comment" name="comment"></textarea>

          <button type="submit">Submit</button>

     }

}

The view show me "System.Web.Mvc.Html.MvcForm":

The method of controller is :

 public ActionResult LeaveComment(int pub, string mail, string comment)

How can I solve it?

EDIT
If I use @using this work well but this crash another Form. The code of the other Form is the next :

@if (Request.IsAuthenticated)
{

            using(Html.BeginForm("LeaveComment", "Publication", FormMethod.Post,

                   new { publicationID = publication.PublicationID, mail = Context.User.Identity.Name }))

            {

                <textarea id="comment" name="comment" style="width: 828px; margin-left: 18px;"></textarea>

                <button type="submit" name="action:LeaveComment" value="LeaveComment"  class="btn btn-default pull-right">

                    <strong>Submit</strong>

                </button>

            }

        }

        else

        {

            <form action="#">

                <textarea id="comment" name="" style="width: 828px; margin-left: 18px;"></textarea>

                <button type="button" href="#login" data-toggle="modal" data-target="#login-modal" class="btn btn-default pull-right" style="margin-right: 15px;">

                    Submit

                </button>

            </form>

        }

UPDATE
I resolve this problem adding using in the leave comment and I deleted the field FormMethod.Post of this post.